Control of Molecular weight and polydispersity in polyethylene/needle-like shaped clay nanocomposites obtained by in situ polymerization with metallocene catalysts

Abstract

In an effort to understand the influence of the shape and area of the nanoclay type used in the in situ polymerization process, two different types of clays (fibrillar and laminar) were employed to obtain nanocomposites. The preliminary results demonstrated that a needlelike shaped clay promotes higher molar mass and better mechanical properties compared with laminar clay. The ultra-high molecular weight of sepiolite/nanocomposites introduces significant problems with processability. Therefore, a new method of polymerization was designed to include two significant changes. The first change was related to the use of a non-isothermal temperature profile and the second to the addition of an additional amount of non-anchored co-catalyst leading to materials with higher fluidity.